Magnetically controlled electric discharge device



Sept. l2, 1950 J. D. coBlNE y MAGNETICALLY CONTROLLED ELECTRIC DISCHARGE DEVICE Filed Jan. 19, 1949 James D. Cob i ne,

by @aand/ nb His Attorney.

Patented Sept. 12, 1950 MAGNETICALLY CONTROLLED ELECTRIC DISCHARGE DEVICE James D. Cobine, Niskayuna, N. Y., assignor to General Electric Company,.a corporation of New York Application January 19, 1949, Serial No. 71,731

My invention relates to electric dischargedevices and more particularly to an electric discharge device of the gas lled type such as may be used to synchronize the operation of a plurality of electrical circuits, or to generate electrical oscillations or electrical noise.

It has for one of its objects the provision of an improved device of this character.

Another object is to provide an electric discharge device of the above type which is of relatively simple construction and yet effectively accomplishes the work usually done by a plurality of such devices.

In general, my invention comprises a gas lled thermionic electric discharge device having a centrally positioned cylindrical cathode, an ionization maintaining anode to establish sultable discharge conditions and a plurality of signal anodes concentrically displaced around the cathode. A substantially uniform magnetic field in a plane perpendicularly cutting the electrodes is rotated so that the magnetic flux passes through the cathode and each signal anode consecutively. Under proper operating conditions, the electrical potentials generated between the cathode and the particular signal anode Whose connecting line is geometrically perpendicular to the direction of the magnetic field consist only of electrical noise; but the potentials generated between the cathode and signal anode combination parallel to the magnetic field direction consist of both electrical noise and strong electrical oscillations. As the magnetic field rotates, the above phenomena rotates with it and simultaneously causes an appreciable change in peak alternating voltage as it passes from one anodeto the next.

The foregoing properties of my new electric discharge device can be used for many different applications in many different types of-electrical circuits. In order to obtain secrecy of communication, for example, the noise voltage can be switched by the rotating magnetic field to a number of communication channels in sequence to provide alternating periods of speech and noise. The oscillating voltage can be used as a synchronized source of radio frequency, `and the corresponding change of peak alternating voltage may be employed for switching or synchronize ing purposes.

The novel features which 1 believe to be characteristic of my invention are set forth with particularity in the appended claims. My inf vention itself, however, together with further objects and advantages thereof may bestbe tun- 5 Claims. (C1. Z50-27.5)

derstood by reference to the following description taken in connection with the accompanying drawings, in which Fig. l is aside sectional View of an electric discharge device embodying my'invention, Fig. 2 is a sectional view `taken along line 2-2 of Fig. 1', Fig. 3 is a chart showing the change in the level of electrical noise and peak alternating voltage as a function of an increasing magnetic eld, Fig. 4 is a chart showing the relative changes in the frequencies of oscillation and the Aamplitudes of these oscillations as a function of an increasing magnetic eld, and

Fig. 5 is a block diagram of a speech scrambling j system embodying my invention.

Referring to the drawings, I have shown my invention in one form as comprising a substantially cylindrical closed tube or envelope I I, preferably glass, containing a gas such as argon or helium at non-critical pressure between 5 to Y 1000 microns. Argon at a pressure in the neighborhood of 100 microns, for example, is quite satisfactory.

A thermionic element, preferably of the indirectly heated type such as a cylindrical cathode 2, extends axially within tube I and is pressed. molded o1' otherwise secured to an insulated sup-- port 3 attached to a base 4. An ionization maintaining anode 5 operating with an electrical potential great enough to maintain a condition of gas ionization within tube I is secured to an end of the tube I and preferably centered on the axis of the cathode. A suitable external lead 6 extends from anode 5 out through envelope I.

A pair of auxiliary anodes, which may be in the form of conductive rods or plates such as signal anodes 'I and 8, are radially displaced from cathode 2; These anodes 'i and 8 face the cathode and are preferably displacedv with respect to each other. Although I have shown only one such pair of auxiliary anodes, it is obvious that a plurality of similar pairs of anodes may be arranged around cathode 2 in order to multiply the effect of a single pair. Although not illustrated in the drawings, suitable terminals for cathode 2, anodes 'I and 8, and heater coil wires Sand I0 are, of course, provided in base 4.

In order to create a substantially uniform magnetic field across tube I, I provide a permanent magnet II having poles I2 and I3 on either side of envelope I diametrically opposite cathode 2. When magnet II is rotated by any suitable mechanical means (not shown), the magnetic field passes through anodes l and 8 consecutiva ly. AlthoughIhavediagrammatically illustrated the magnetic field asicreated byapermanent magnet Il mechanically rotated, an alternative system of electromagnetic coils carrying suitably Varying currents may, of course, be employed.

In typical circuit operation, the ionization maintaining anode potential with respect to the cathode is high enough to cause ionization of the gas, and the magnetic field is strong enough to suppress completely the oscillations in the particular anode-cathode combination perpendicular to the magnetic i'ield. In a tube of conventional size, anode voltages between 100 to 1000 volts and a magnetic field intensity ofbetweenZOto 100 gauss are quite satisfactory.

The potentials between the .cathode-anode combination not directly affected -fbyilthelm'a'gnetic field, i. e., the anode-cathode combination whose connecting line is in a planeparallerto,

the direction of the field, normally consist of a iA-n appreciation of its versatility can be obtained by reference to Fig. 5 in which I have Shown my n"ir'iventi'on asap'plied to a speech scrambling cirlow frequency oscillation having a 'frequency below 300 kilocycles, and a high frequency oscillation having a frequencygreater than 500 kilocycles, superimposed upon random electrical noise and upon possible harmonics of both oscillations. The oscillation of the lower frequency is apparently a function of the position of the electrodes, the magnitude of discharge current, and the type and pressure of the inserted gas. It is virtually independent of external circuit constants. IThese oscillations may be considered as a positive ion plasma oscillations whose energy is Itransmitted to the external circuit by velocity modulation of the electron beam passing directly from cathode to anode.

The electrical characteristics of an anodecathode combi-nation as a transverselmagnetic field is introduced vand increased due to the rotation of magnet H are plotted in Figs. 3 and=4 as a function of the magnetic eld. It will ybe appreciated that although the curves shown rin Figs..-3 and 4 are typical, theyvare only exemplary `and for purposes of discussion. Considerable variation can be, of course, effected by tubedesign, gas pressure, operating potentials andother variables.

The low frequency oscillations shown in an exemplary curve F1 of Fig. 3 do not change -in frequency, but decrease in amplitude as illustrated `by curve Fi until they become merged in the noise level and completely lose their' ridentity. This phenomenon may be considered as caused by the removal by the magnetic field of electrons that would otherwise reach the anode without collision with gas atoms from the current reaching the anode.

The higher frequency oscillations shown in auxiliary curve F2 are less stable vand increase in frequency as the magnetic iield is introduced, but decrease in amplitude as illustrated by Acurve F2 to iinally also merge in the noise -level under the iniiuence of a suiiiciently strong magnetic eld. Referring to Fig. 4, the noise level illustrated by the curve so labelled rst decreases and then slowly increases. The rotation -of the magnetic field causes only a slight reduction of average current but an appreciable changelin peak alternating voltage as shown by the curve bearing this legend.

Therefore, as the substantially uniform mag- -netic iield4 is rotated from a parallel direction to a dection that is-perpendicular with respectto a particular signalianode-cathode 1line,the'fol lowing marked electrical "changes occur: The characteristic oscillations are suppressed, .the noise level is increased, andltherpeak alternating voltage resulting from both' the loscillations and "cuit'ffor'preserving secrecy of communication. A `:sourceofsilinidirecticnal electromotive force, such :afs battery F4, isvconnected through suitable impedance elements't to the ionization maintaining anode 5to :establish suitable discharge conditions and to the auxiliary anodes 1 and 8. The

electrical #noise generated at anodes 1 and 8 is applied through respective conventional noise .amplifiers I6 and li to a /pair :of :intelligence modulated radio frequency output-channe1sllA and B, respectively. These noise amplifiers preferably include. amoscillationV rejecting -filter z network such as azparallel tuned circuit to reject the radio frequency `oscillations within-tube vI.

When the direction of -themagnetic'iield generated by magnet il is in a position parallel :to the line connecting cathode-f2 and anode '1, the peak noise voltage between theseelectrodes -is-'at its minimum value, and the intelligence signal applied to channel A from a suitable modulation source E8 can be separated from the low level of random electrical noisereachingthefchannel A through the noise amplifier IS. As the: magnetic field is rotated toward a direction.perpendicular to the anode l-cathode 2 linetheunoise-leve1 increases until the signal voltage is "mergedsin the noise voltage to becomecompletely Aunintelligible. Simultaneously, the magnetic vfieldis also approaching a direction parallel tothe line connecting anode and lcathode 2, therebydecreasing the noise voltage which is -beingapplied to communication channeliB through noise-ampliiier I7. Therefore, as v'magnet Il is rotated, the output of channel A consists of intelligence signal voltage alternating with noise, andcthe output of channel B has V-a similar pattern out of phase with channel A. If both 'channels A and B are modulated by the same continuing signal from source i8, a proper receiving system can combine both channels, eliminate the noise by.a synchronized switching circuit and Vreceive only the intelligible signal. The rate of alternation of signal andnoise-is-of course, ydetermined by the speed of rotation ofmagnetf Il.

A modification of the foregoing speech scrambling system may obviously be made `by using the oscillations generated at Aanodes l and 8 vas asource of radio-frequency for ther communication channels as illustrated by thewdashed lines of Fig. 5. ,These oscillations Amay lbe `appliedto the channels through conventional tuned-"amplifiers, blocks 9,211, andiarepresenp duringrfthe interval on each channel that the intelligence signal is easily Fdiscernable over the noise voltage. Many other applications of .my invention-,such as the operation ofrelay circuitslby the variation in `the noise level or: vby thechange inlthecpeak alternating voltage as magnet Il is r'otated,will obviously :occur .to thosefskilled inthey art. y

-S'Sli/'hi-lehave shownaf particular embdinient of lmy invention, fit-is'I-"to -beiiu'nderstood -that'fI do vnot wish to be limited theretofsincemjaiiy mbdiiications V*n'iaavtbe fma'de, and f lI, A-therefore.'

contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric discharge device comprising a sealed envelope containing a gaseous medium and enclosing a longitudinally extending cathode, a plurality of signal anodes located in spaced relation around said cathode and an ionization maintaining anode spaced from said cathode and said signal anodes, input connections to said cathode and said ionization maintaining anode for supplying voltage therebetween to ionize said gaseous medium, and a rotating magnetic field producing means surrounding said envelope for providing a substantially uniform transverse magnetic field which rotates around said cathode through each signal anode consecutively to vary the electrical characteristics of said ionized gaseous medium between said cathode and said signal anodes.

2. An electric discharge device comprising a gas filled hermetically sealed envelope containing a thermionic cathode extending along the longitudinal axis thereof, at least one pair of signal anodes circumferentially spaced around said cathode and an ionization maintaining anode axially spaced from said cathode, electric connecting means for supplying voltage to said electrodes to ionize the region between said cathode and said signal anodes, and a magnetic system external said envelope in a plane which cuts said cathode and said signal anodes for producing a rotating substantially uniform magnetic field which diametrically traverses said envelope through said cathode and passes through each signal anode consecutively during its rotation to vary the electrical characteristics of said ionized region.

3. An electric discharge device comprising a sealed envelope containing an inert gaseous medium, a cylindrical thermionic cathode extending within said envelope along the longitudinal axis thereof, a pair of signal anodes located at 90 degree circumferentially spaced points around said cathode within said envelope, an ionization maintaining anode centered on said longitudinal axis within said envelope in axial spaced relation to said cathode, independent input connections to said cathode, said signal anodes and said ionization maintaining anode for supplying voltage thereto to ionize the region between said cathode and said signal anodes and means including a magnetic system having poles on diametrically opposite sides of said envelope in a plane which traverses said cathode and said signal anodes for producing a rotating magnetic field which revolves around said cathode through each signal anode consecutively to vary the electrical characteristics of said ionized region.

4. An electric discharge device comprising an envelope containing a gaseous medium and enclosing a centrally positioned thermionic cathode, at lease one pair of signal anodes circumerentially spaced degrees around said cathode and an ionization maintaining anode spaced from said cathode and said signal anodes, independent input terminal connections to said cathode, said signal anodes and said ionization maintaining anode for supplying voltage thereto -to ionize said gaseous medium and establish electrical oscillations between said cathode and said signal anodes, and a magnetic system having poles on diametrically opposite sides of said envelope for producing `a rotating magnetic field which revolves around said cathode through each signal anode consecutively thereby to suppress said oscillations intermittently.

5. An electric discharge device comprising an envelope containing a gaseous medium and enclosing an axially extending thermionic cathode, at least two signal anodes circumferentially spaced around said cathode and an ionization maintaining anode axially spaced from said cathode and said signal anodes, input terminal connections to said cathode and said ionization maintaining anode for supplying voltage therebetween to ionize said gaseous medium and to produce a noise voltage ibetween said cathode and said signal anodes, and means for varying the level of said noise voltage comprising a magnetic system having poles on diametrically opposite sides of said envelope for producing a rotating magnetic field which revolves around said cathode through each signal anode consecutively.

JAMES D. COBINE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,962,158 Smith June 12, 1934 2,164,538 Meier July 4, 1939 2,217,774 Skellett Oct. 15, 1940 2,221,743 Wagner Nov. 12, 1940 2,221,744 Henry Nov. 12, 1940 2,225,689 Demuth Dec. 24, 1940 2,248,712 Litton July 8, 1941 2,345,115 Hall Mar. 28, 1944 2,390,884 Jansky Dec. 11, 1945 2,391,967 Hecht et al. Jan. 1, 1946 2,404,920 Overbeek July 30, 1946 2,432,608 Desch et al Dec. 16, 1947 2,433,813 Hilliard Dec. 30, 1947 2,440,639 Marmont Apr. 27, 1948 Certificate of Correction Patent No. 2,522,209

eptember 12, 1950 JAMES D. COBINE It is hereby certified that error appears in the prlnted speclicatlon of the above numbered patent requlng correction as folle Column 3 Ime 13, for 100 gauss read 1000 gauges; and that the sald Letters Pa [SEAL] THOMAS F. MURPHY,

Assistant @ammissioner of Patente.

Certificate of Correction Patent No. 2,522,209

eptember 12, 1950 JAMES D. COBINE It is hereby certified that error appears in the prlnted speclicatlon of the above numbered patent requlng correction as folle Column 3 Ime 13, for 100 gauss read 1000 gauges; and that the sald Letters Pa [SEAL] THOMAS F. MURPHY,

Assistant @ammissioner of Patente.

Certificate of Correction Pat-,ent No. 2,522,209 September 12, 1950 JAMES D. COBINE Itl is hereby certified that error appears in the printed specication of the above numbered patent requiring correction as follows:

Column 3, line 13, for 100 gauss read 1000 gauss;

and that the .said Letters Patent should .be read as corrected above, so that the same may conform to the record of the casein the Patent Oce. Signed and sealed this 9th day of January, A. D. 1951.

[SEAL] THOMAS F. MURPHY,

Assistant Uommz'ssz'oner of Patents, 

